In 1999 Ramsey was cleared of brown rats which had been accidentally introduced to the island via shipwrecks in the 1800’s and were having a devastating impact on the island’s ground nesting seabird population. Puffins had become extinct, there were no storm petrels and Manx shearwater numbers were severely curtailed.
Since then puffins have continued to elude us as a breeding species but storm petrels were found nesting for the first time in 2008. However it is the Manx shearwater that is the real success story. From just 850 pairs in 1998 the population has bounced back to 3,800 pairs by 2012.
Given that the bird does not breed until it is 5 or 6 years old some of this increase must be down to immigration from the huge nearby populations on Skomer (300k pairs) and Skokholm (45k pairs)
In a bid to unravel the story behind the increase we have been ringing shearwater fledglings on Ramsey since 2010. We were delighted to start seeing some of these birds again for the first time this year. Birds ringed as fledglings in 2011 are now returning to the island at 2 years of age to prospect for future breeding sites and partners. It was amazing to think that the birds in my hand could have been to Argentina and back twice since I last held them!
Manx shearwater fledgling on Ramsey Island - some down is still left on this bird but the adult feathers beneath are fully formed
Shearwaters have evolved to breed on islands as they offer safe breeding havens free from ground predators. They are nocturnal on land as their bodies are adapted for swimming. Their legs are set far back which makes walking cumbersome and would leave them prone to attack by gulls if they came ashore during daylight hours. When alien predators such as rats are accidentally introduced the effects can be dramatic. These birds have no evolutionary defence mechanism against such a predator. Eggs and young are particularly vulnerable and it is for this reason that Ramsey had so few breeding pairs of shearwaters when rats were present. Skomer and Skokholm have never had rats – the contrast in breeding numbers is enormous.
Visitors to the island may smile when they are asked during the crossing to check their bags and luggage for any unwanted stowaways but there is a serious point to it. The video below is a stark reminder of the impact introduced predators can have on ground nesting seabirds. The film shows a rat attacking a Cory’s shearwater chick (a relative of the Manx shearwater). This same scene would have been played out night after night on Ramsey during the breeding season up until just 12 years ago. We are thankful to those who worked so hard to allow the shearwaters to breed here successfully once more (especially WMIL) and why we are so careful today not to see it happen again.
(film from U-tube channel of Francesco De Pietro)
There is no overnight accommodation on Ramsey but to experience a Manx shearwater colony in all its glory you can book accommodation on either Skomer or Skokholm. See the Wildlife Trust South and West Wales website for more details.
To find out more about the remarkable life of the Manx shearwater the monograph by Dr Mike Brooke is an excellent read.